In a medium bowl, whisk together flour, cocoa powder, baking powder, baking soda, and salt until the mixture looks uniform and lump-free.

In a separate large bowl, combine granulated sugar, brown sugar, oil, and milk, whisking until smooth and slightly glossy.

Add eggs, vanilla extract, and peppermint extract, mixing until fully incorporated and lightly frothy.

Gradually add the dry ingredients into the wet mixture, stirring gently until just combined and no dry streaks remain.

Slowly pour in the hot coffee while whisking, creating a smooth, slightly thin batter with a rich chocolate aroma.

Transfer the batter into the prepared pan, smoothing the surface evenly.

Bake until the cake rises and a toothpick inserted in the center comes out clean with a few moist crumbs.

Allow the cake to cool completely in the pan, letting the structure set and flavors develop.

Beat softened butter until creamy and pale, then add powdered sugar gradually until fluffy.

Mix in vanilla extract, peppermint extract, and salt, whipping until the frosting becomes light and spreadable.

Spread the frosting evenly over the cooled cake, creating soft swirls on the surface.

Sprinkle crushed peppermint candies over the top for a festive finish and gentle crunch.